The Science between a Plant Based Diet and Health

Tushar Mehta, M.D.

Hi, Sanjeev, How are you doing? I’m doing well, thanks.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Good. Thank you so much for joining me today. So I just want to get right into it. You know, you’re an expert in plant-based diet, I know, for the last like 30 years, since I’ve known you. And so I want to understand the journey, like how did you actually get involved into this space and what really got you interested?

Tushar Mehta, M.D.

Right, well, I think the journey started maybe in high school. Like so many teenagers, you get interested in world issues, human rights issues, environmental issues, and also issues around surrounding animals, ethics, and so forth. That got me interested to begin with. But my interest in the nutritional aspects really started sometime during and especially after medical school. That really influences us to think scientifically, to learn about evidence-based medicine. And around 2012 i started realizing that there’s actually a lot of data and studies being done around plant-based diet that I didn’t know existed actually. So I started getting into all that and reading more and more about it. And the volume of literature coming out has yearly kept up at a very fast pace and is actually accelerating. So I became very interested in that body of knowledge and also became an interested in the information, the data surrounding animal agriculture versus plant-based diet in the environment. And yeah, that’s how it sort of got going.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Okay, so maybe just for our viewers, if you could just give a definition, because I think people sometimes get confused. What does this mean, plant-based diet, versus let’s say vegan or vegetarian or pescatarian or paleo? If you can kind of just give a little bit of a… If we can set some definition right at the beginning, that would be helpful.

Tushar Mehta, M.D.

Yeah, I think it’s a good idea. So a plant-based diet is one where the majority of a person’s protein and calories comes from plant-based sources. So that is not synonymous with a vegan diet. A vegan diet is an exclusively plant-based diet. And that is one type of plant-based diet, as is a vegetarian diet, as is also what we call flexitarian and Mediterranean diets, the traditional Mediterranean diets and those which are studied in and published in so many articles. Those are all forms of plant based diet, where the majority of calories and protein come from plant-based sources. Now there may be a small amount, of course, that comes from animal-based foods according to each of those different diets, right? But except for the vegan diet, where there would not be any, although in some studies, people who are classified as vegans may consume a small amount of animal products once a month or so. And they’re still put into the category of vegans because the quantity is very small.

Sanjeev Goel, MD, FCFP (PC), CAFCI

So how would you… You actually said like in 2012 you started becoming aware of the research, the strong amount of research, looking at health benefits of these types of diets. So if you could just maybe break it down in broad categories of what does that research look like?

Tushar Mehta, M.D.

Yeah, that’s a good way to start out. So if you’re looking at plant-based diet, there’s so many studies out there, and there’s all kinds of studies saying, “Oh, there’s a benefit for this or a benefit for that.” But if you were gonna look and say, “Okay, what are the main things? Let’s cut out the minutia and look at the main category.” So the main categories would be all-cause mortality, cardiovascular disease and cardiovascular mortality, certain chronic diseases related to sort of metabolic syndrome. So diabetes, dyslipidemia, hypertension, obesity, those ones, certain types of cancer. There’s a more moderate benefit as compared to the cardiovascular disease and metabolic diseases. 

There’s a more moderate but significant benefit related to certain types of cancer. So there’s a slight benefit, let’s say, for all cancer, sort of the group of all cancers, if you just look at all cancers combined, right? But also breast and prostate cancer, colon cancer, and some other cancers that are less common, things like pancreatic cancer, for example, but prostate, breast, and the total cancer categories are the more important ones. There is mounting benefit for brain health in terms of dementia prevention. Now you mentioned to me Alzheimer’s, but I would rather classify that as sort of a general dementia, so there’s more data-

Sanjeev Goel, MD, FCFP (PC), CAFCI

We’re hearing the term of type three diabetes, as Alzheimer’s is type three diabetes. So I don’t want to necessarily jump ahead, but what could be the reason, like why would a plant-based diet have impact on brain health? It doesn’t seem, you know. I just curious.

Tushar Mehta, M.D.

I think a lot of the, yeah… So when you talk about mechanisms, so I’m more of a clinician. I do focus more on the clinical science as opposed to the mechanisms, you know, the basic science mechanisms of disease and biomarkers. I’m less interested in biomarkers and mechanisms than I am in actual clinical outcomes, okay? That’s my bias as a physician and as a clinician and maybe as an emerge doc as well. But I think at the end of the day that’s the nuts and bolts things that we worry about. But in terms of biological mechanisms, there’s many plausible reasons, the first of which is vascular health. So when people have less vascular disease and more healthy vasculature, right, obviously that relates to heart disease, but it also really relates to other body systems. 

So there’s evidence regarding plant-based diet and peripheral vascular disease. And there’s evidence for things like back pain, because when you have stenosis in arteries that go to the spinal column and the various structures there, it has shown that people who have more vascular disease probably have more osteoarthritis as well as back-related problems. So there’s some evidence there, and that’s probably where the brain health benefit comes in too, that, again, healthy vasculature means the smallest of the arteries and arterials stay well perfused, and that will benefit brain health. Now there’s a whole cascade of events, because let’s say you have some vascular disease and there’s relatively less blood flow. 

There’s also consequences of inflammation, oxidation, oxidative stress, all those kinds of mechanisms also kick in. So what we’re talking about is a very generalized sort of idea of mechanism that healthy vasculature leads to better end organ perfusion, but there’s many more mechanisms involved still. Other than that, there are theories about amino acid profiles, about different things that affect glycemic index when you’re eating whole plant foods, because the benefit is more and more shown to be regarding whole food plant-based diet, not just any kind of plant based diet. And so it’s, there’s glycemic control issues. 

There’s inflammation issues. When you eat food, there are so many nutrients involved, so many phytochemicals, right? It has never shown to be true that you can isolate one of those compounds and take it as a supplement and get the same benefit, because you’re eating a package with thousands of things in it when you eat whole-plant food or animal-based food. And that package contains things, whether it be antioxidants or other things that are also beneficial. On the flip side, there may be some detrimental effects of animal-based foods. So part of the benefit may be good things that are in the plant-based foods and some detrimental things that you’re excluding from animal-based foods. So a combination of reducing certain things and increasing others. That’s a general approach to the mechanisms, and you can always have a talk where we go into more details. But as I mentioned, it’s the clinical evidence that is of the most interest, I think.

Sanjeev Goel, MD, FCFP (PC), CAFCI

So you were mentioning that the research has showed benefit on metabolic syndrome, cardiovascular disease, a modest benefit in cancer. Can we get a sense of how big of an effect is that? Do we have a sense, like, is this like a 30% reduction? Is this like a 5% reduction in risk? Do we have a sense of what that is?

Tushar Mehta, M.D.

Yeah, I mean, those are… I think what we want to do when we talk about these kinds of things is we want to look at some of the studies that have done and see the types of benefits that are going on there. And now there’s two things. One thing is looking at a study and seeing what kind of benefits are present there, and then trying to extrapolate that to more general populations and things. That’s one thing. The second thing is that there are always limitations to a study. For example, a study may be done looking at people’s plant-based diet, and say there’s X amount of benefit. And you have to look at the parameters of the study. 

For example, the study may include people in a general sort of more plant-based diet scale, but they’re not necessarily looking at the most optimized plant-based diets. So then we have to think to ourselves, okay, when you’re looking at different studies, studies that look at also diet optimization and the benefits, and think of… Here’s a certain amount of benefits. 

The benefits may actually be more, or the benefits may be less if people’s diet quality is less, right? And it also looks at the competitor group. So in many studies, the meat-based groups actually are much more plant-based compared to the general population, because there’s sort of a healthy volunteer effect. People who volunteer to be in studies tend to be more health conscious in the first place and tend to eat more plant-based in the first place. So even the meat-based group is not as bad as the general population. And the other thing is that, as time goes on in modern day, we have more and more medical interventions, right? We had a guy came in, I was working at the emerge last night. He came in with a STEMI. He had a sort of occlusion, myocardial infarction, where an artery is blocked. And we had him up to the cath lab within a half an hour of him being in the emergency department, half an hour, 40 minutes of him being in the emergency department.

Sanjeev Goel, MD, FCFP (PC), CAFCI

That’s awesome.

Tushar Mehta, M.D.

So that didn’t exist 20 years ago. And as we get better and better at treating these diseases you might see a narrower gap between people eating unhealthy foods and more healthy foods, because we’re able to use technology, medications, and medical systems to attenuate the differences. But now having said that, I’ll finally answer your question . I’m gonna go to a couple of studies here and look at… I sent you some studies lists. I have these reference lists which I think are sort of a compilation of some of the most important and best studies. And it’s not comprehensive. 

There’s lots of other studies that I think could also be on the list, but I just don’t want to overpopulate the list as well. But here’s a great study from 2021, “Association of Major Dietary Protein Sources with All Cause Mortality and Cost Specific Mortality,” prospective cohort study, Journal of the American Heart Association, and it’s over 100,000 women from the Women’s Health Initiative in there. And let’s see, so for comparing those who eat the most plant-based to the least plant-based in quintiles, there was all-cause mortality benefit of about 9% in a study that went from 1993 to 1998. 

So that’s about a five-year, over those five years, you’re looking at a time span there, there was 9% less deaths in the people who eat the most plant-based versus the the least plant-based, and cardiovascular mortality was decreased by 12% in that study, and dementia mortality decreased by 21% in that mortality. And that’s just over five years. So if you extend that for a longer time, would you see even a stronger signal? And so that’s an example of some of the things, but if you can invent a pill that you could sell and say, “Hey take this for five years, you have a 9% less chance of dying,” people would jump all over that, but I think this is good, because it’s something that you can do and it doesn’t cost you anything extra and it doesn’t require you taking a pill.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Right. A lot of these studies, I remember even when I did the look at the literature some years ago, were observational studies, like this women’s health study, where they followed people along. There were not necessarily intervention studies.

Tushar Mehta, M.D.

That’s right.

Sanjeev Goel, MD, FCFP (PC), CAFCI

They looked at people like their parents or something and what they came from, you know, China or Japan or whatever. And the kids had a Western diet. And they said that the rate of heart disease was much higher and things like that. We kind of had to infer that the… because we can’t necessarily control for all the other variables, but it seemed like obviously diet had had a big impact. But I think that Dean Ornish was quite… He has some pretty landmark studies that looked at actually intervention of reversing heart disease using a vegetarian diet. Do you want to comment on that?

Tushar Mehta, M.D.

Yeah, so Dean Ornish published two papers regarding his lifestyle and heart study, and they were interventional studies, as you mentioned. They’re kind of historical. They’re pretty old. We still refer to them. And I still think they’re interesting, of of great interest, but I don’t hang my hat on those particular studies. I don’t hang my hat on any one particular study. Even this all-cause mortality study I mentioned, if you look at the reference list I showed you, there’s multiple studies talking about all-cause mortality. And that was only one of them. There’s other ones there that have even a stronger signal, but that one, where he had put people on a very, very low fat extremely low fat, whole food plant-based diet for a year and found a tremendous decrease in recurrent heart disease. 

So he had a population that already had severe heart disease, and then he used this intervention. He found on the patients that he used the intervention with, they had very, very low rates of recurrent MI or revascularization. And then he followed these same people for five years out. Or I think actually that may be Caldwell Esselstyn. You know, there’s Caldwell Esselstyn and there’s Dean Ornish. They both have done kind of similar studies, but in those days when they followed people for a longer period, they found, again, people who stuck with the diet had much better outcomes, essentially. 

So those are interventional, but it was not a randomized control trial. It was interventional study, but it’s not randomized control, but they had very, very dramatic results. And I think it behooves us to actually fund… there’s a few cardiologists that are very well noted to be promoting a whole food plant-based diet, and people who criticize those studies, the response is that we are responsible now to follow up on those things and do a larger study that is randomized or what have you. So that’s what we need to do. And the studies that you mentioned just now, like sort of looking at people coming and immigrating from Japan to America, looking at the children versus the parents and stuff like that, those studies do exist. Those are older studies. You know, those are published like say in early 2000s or the 1990s, but you’ll see that the more contemporary studies are also cohort studies. 

The bigger ones are cohort studies. But there are much better defined populations, very large populations, followed for longer periods, like the one I just mentioned, looking at over 100,000 women, right? And we’re looking at those kinds of numbers, and that was five-year study, but there’s other studies that are going for a much longer time. And those are good because they’re, especially data that comes from the nurses’ health study, physicians’ health study, populations that are pretty educated, little bit more uniform in terms of their socioeconomic and education status, and sort of know how to sort of fill out forms and give good data feedback to the people who are doing the study. So there’s studies based on those kinds of groups, and although not randomized, I think there’s really good data. At the same time, there are randomized studies coming out that are, of course, much smaller, because you can’t randomize 100,000 people in a dietary study for X number of years, but there are randomized trials that also come out too.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Right. Okay. You know, some of our viewers, I think I know a couple of my friends, even, who have gone to a plant-based diet after watching the Netflix special “Game Changers,”

Tushar Mehta, M.D.

“The Game Changers,” yes, yes.

Sanjeev Goel, MD, FCFP (PC), CAFCI

You’ve seen this, which they talked about these young guys who, one of them took a vegetarian meal and the other one took a high fat meal, and then they measured their nocturnal erections.

Tushar Mehta, M.D.

Oh, erections. Yeah. I don’t think that’s quite… I think it was very dramatic, but I don’t think it was very scientific. It was very dramatic, but not scientific. So I wouldn’t include that study in my database, but I think it was entertaining.

Sanjeev Goel, MD, FCFP (PC), CAFCI

But isn’t it, the microvascular, I mean, there may be changes that are happening on a microvascular level. I mean, I’ve interviewed some other researchers in the space that this are… The capillaries and microvascular changes depending on a high-fat meal break quickly. It can last-

Tushar Mehta, M.D.

There could be. You know, I haven’t seen a study on that particular thing and, you know, nitric oxide and all that kind of stuff that people talk about, involved in the the physiology of an erection. But putting that aside, you know, long-term sort of preservation of erectile function does involve the microvascular and some of the sort of macrovascular elements of the penis. So I think there, I’m not sure if I have a couple of studies regarding that. There’s more anecdotal evidence though, right? I think that should be the subject of a study as well. Looking at people on whole food plant-based diet, guys, and looking at erectile function. 

I can quickly scan my database for a couple of studies regarding that, but that’s true. I think that’s very well within the means of sort of long-term benefits is preserves erectile function. And it’s also known that loss of erectile function is a precursor to heart disease in many cases, right? When a guy loses erectile function, actually within the next few years, he’s actually at higher risk of a heart attack. So that’s something that we want to also keep in mind, that there’s a common mechanism that’s happening there. 

Sanjeev Goel, MD, FCFP (PC), CAFCI

Right. What are your thoughts about, these days we’ve had a lot of, I guess craze or interest in ketogenic diets, paleo diets, and you’ve mentioned Mediterranean, lots of research studies on that. Where do you think plant-based fits into this? And how do we compare these? What do you tell your patients who are… You know, ’cause ketogenic has had very positive aspects on weight loss and increasing insulin sensitivity. So how do you put this together?

Tushar Mehta, M.D.

Yeah, that’s a good question. I think the problem is that people are not necessarily looking at long-term outcomes, and at the same time, there’s a lot of industry influence in this whole thing. So when you’re looking at these, the low carbohydrate diets have been promoted for a long time. We’re talking about going back to like the seventies and eighties. There’s people like Atkins and then, you know, supported by the animal agriculture industry. And then when that gets a little bit unpopular and this guy gets a heart attack and dies, you know, then there’s the Zone diet, right? And there’s the South Beach diet. And then there’s the paleo diet comes in, and then there’s keto diet, and the industry keeps repackaging different forms, and that’s the carnivore diet as well, right? They keep prepackaging the sort of low plant food or low carb diets in different, different ways, and marketing them back to people. 

All right? So definitely, the main mechanism for weight loss is really calorie reduction, okay? And we have good articles in the database, again, showing that the main mechanism is calorie reduction. If you eliminate the entire, you know, majority of your carbohydrate intake, right? Even if you increase your fats and protein intake, chances are that when somebody starts with a bad diet to begin with, these are people starting with bad diets, and you cut out a whole bunch of sugar and junk and carbohydrates, you’re gonna lose weight, right? If you cut out all your fat, you’re gonna lose weight too. Okay, either way you’re gonna lose weight. The question is which methods of diet can be sustained long-term and lead to long-term benefits. 

And the evidence consistently shows that people who are on low carbohydrate diets in the long run have higher mortality, have higher rates of heart disease, and have higher rates of cancer, despite the fact that in the short term they may have weight loss, and they may have, for a short time, benefits in terms of biomarkers, like just their blood sugars and things like that may get better. But it isn’t healthy for you in the long run, right? There may be exceptions to this, maybe a vegan keto diet or a vegan high protein, low carb diet. Maybe that’s better. 

Okay? But I would caution people against, I think that it probably is better because there’s a lot of more whole plant foods, low saturated fat. Hopefully you’re not eating things like coconut oil, which is a plant food, but it’s, and palm oil, which is high saturated fat. I don’t think those are necessarily good for you. In fact there’s evidence that they’re not, but you may be able to do a plant-based version of these things, but I would caution somebody for doing that kind of thing, even plant-based in the long run. We don’t have evidence for it. 

So I’m not gonna promote something that’s not evidence-based, but we do have evidence that these low carb diets high in animal products have long-term consequences. And in the list I’ve shown you there’s many articles in the carbohydrates section talking about the whole grain carbohydrates do have a consistent, significant signal regarding reduced mortality, reduced cardiovascular disease, reduced diabetes, and some reduction in cancer. Modest, but consistently present. Okay. And yeah. But low quality carbohydrates, refined carbohydrates, that’s all your white flour, white rice, Ramen noodles from Mr. Noodles, right? The sugars and all that stuff consistently are shown to be bad for you. 

So that’s why I mentioned that it’s not just about plant-based diet, it’s about a high quality plant based diet where you’re whole foods, low fat, you know? And the Mediterranean diet. When we talk about Mediterranean diet, the Mediterranean diets that are studied are essentially examples of plant-based diets. They are majority plant-based. They emphasize a lot of beans and lentils and things like that. There’s some particular things that they may say, okay, have olive oil and things like that. I would caution people not to eat too much olive oil. A little bit is okay. But when they show benefits, again, it’s again, the benefit… People think, “Hey, Mediterranean’s fish.” Actually Mediterranean means more beans and lentils and whole grains and those kinds of things, and fish is not a huge part of it.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Right. What are your thoughts about the concern about gluten, some of these grains people, you know, potentially are having some type of sensitivity. I’m not sure, but the health impact of this. ‘Cause that could be major part of a plant-based diet.

Tushar Mehta, M.D.

Right. So what you’re specifically referring to, I think, is what we call non-celiac gluten intolerance, okay? So people with celiac disease have a definite allergy to gluten and must avoid gluten. There’s a high prevalence in certain populations, I think, such as Ireland. But otherwise it’s a low prevalence of this kind of disease. Now there’s a whole fad that came out over the past, whatever, 15 years, saying that gluten is bad for you, carbohydrates are bad for you, and all this kind of stuff. And a lot of fear-mongering that was going on. And when they did studies on people regarding non-celiac gluten tolerance, where they did, actually randomized controlled trials, where they ate like, for one week had a meal that had gluten and then another week had a meal that didn’t contain gluten. 

And then they crossed the people over and so forth. And they didn’t know whether they were eating gluten or not. They were given food which had gluten or not, like a muffin, for example, not knowing if there’s gluten or not in there. They do these randomized trials. They found that most of the people who thought they were gluten intolerant, it’s almost 50% did better on the gluten muffin than the non-gluten muffin. But there was a small percentage of people who actually felt a little bit better, let’s say, on the muffin that was non-gluten. So these are self-identified people with non-celiac gluten intolerance. 

But for the most part, it was a wash. For the most part people thought they were gluten intolerant and they actually said they felt better on the gluten, the muffin with gluten in it. And there’s very little scientific evidence that gluten is bad for you, but there’s a lot of scientific evidence that refined carbohydrates are bad for you. So when people are cutting out carbohydrates and feeling better, it’s because the majority of people’s carbohydrate intake is from unhealthy sources to begin with. Our general diets contain these highly processed carbohydrates, far and excess of whole grains. And when people cut out this food as a class, they may see some benefits because they’re not eating the healthy stuff to begin with, but what would rather be beneficial is eating whole grains consistently and consistently excluding the refined carbohydrates. Maybe a little bit once in a while, but really keeping that stuff to a minimum.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Right, okay, no, that’s very helpful. What are your thoughts about… One of the things that I’ve kind of thought about is that perhaps the type of food or the type of diet we have needs to vary with the time of year. Like perhaps that’s, you know, there is some need for change and it’s not always the same diet, but how do you feel about that? And then also where do you think fasting fits in, intermittent fasting? These are also really hot topics these days, and where do you fit that into a different diet.

Tushar Mehta, M.D.

Yeah. And it sounds like, sort of two questions. One about fasting, and then one about like the variation of diet throughout the year. When it comes to… I think variety’s the spice of life as long as our variety is within healthy parameters, right? If somebody says “Variety’s the spice of life. Hey, once in a while, I’m gonna use cocaine,” right? I’m gonna beg to differ. I think you should probably avoid cocaine, and you know, variety, you know, there’s all kinds of things that maybe should not be rotated into that variety. But I think that we should be having a lot of variety of our diets. 

And I think in this age where we are really globalized, okay, we are really globalized, and we can get to this, but the impact of our diet also has a global impact on the environment, as well as local impact, but especially a global impact. And so if we’re trying to fix these problems and do better, we can take advantage of the global variety of plant-based foods. There’s incredible plant-based foods that come from Europe, that come from African continent and countries, from Asia, from South America, from north America and the Americas where a lot of the indigenous people, people think of them as hunters, but the largest populations were agriculturalists, right? 

And the three sisters beans, corn and squash, we’re growing right from the Southern Ontario right down into, through the U.S. and Mesoamerica, and Central America, South America, these were staple foods, right? So this incredible variety we can take advantage of, for sure, but I don’t think that necessarily, “Oh, it’s winter. I have to eat steak,” or something like that. I don’t think there’s evidence for that. If you can show me credible studies showing that you’ve got to eat these things because it’s wintertime. And if it is winter, the nice thing is that we have fantastic high protein and all kinds of plant-based foods that are great for any time of the year, I think. Yeah.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Mm-hmm. Okay.

Tushar Mehta, M.D.

The other thing is that anywhere you go around the globe, in like 95% of the areas around the globe, there are fantastic high protein plant-based foods that can grow in those areas. There are beans and lentils that are adapted for hot conditions, cold conditions, dry conditions, wet conditions, et cetera. So taking into account the local conditions and cultivars of plants that grow in those places is a really fantastic thing to do.

Sanjeev Goel, MD, FCFP (PC), CAFCI

And then the fasting, what are your thoughts on the fasting?

Tushar Mehta, M.D.

Fasting, yes. Well, I’m not an expert on fasting, so I’m not going to make too much comment on that. But what I am gonna say is that portion control is important. Because in our society, see, as you know, I used to work in a village in Indiana, and I’d spend one month working every year for about 10 years in this village at a sort of a community hospital that was run by volunteers and donors and so forth. And it was kind of a charitable organization. And in the area, it’s a rural area, lots and lots of farmers, okay? Now these farmers, they could eat like a stack of 10 rotis in a meal. I’ve sat and eaten with them, okay? I can eat two, all right? Now these guys are skinnier than I am, and I’m not a really big guy or anything like that, but they can eat that much. 

If the rest of us who were volunteering and living in, let’s say, the city and coming to volunteer, whether it’s from India or the West, we would become obese. Because those guys are working in the field all day so hard. Our level of energy expenditure is nowhere near that. So our energy intake should be closer to our energy needs in our expenditure. And we exceed that over and over again. So whether you’re plant-based or not plant-based, people do need portion control. Intermittent fasting, and fasting, and those kinds of things, if it helps you with that process, I think that’s good for you. And I think also just, this is my thought process, not me being evidence-based about it, but I think it’s good that, you know, humans evolved eating at times and also going times without food. 

It’s not like we constantly had something fed to us so that we would never be hungry. You know, I think some amount of hunger is a natural process. And when you go running or have a long workday and if you don’t eat for a while, and you’re training your body to do that, there’s probably some benefits. But this is just me speaking in terms of intuition, rather than being science. I want to be very clear about that, okay? But I know that there are studies done on intermittent fasting and whatnot, but certainly I think portion control and your control of net caloric intake is important. While mentioning that, there is good evidence that people on whole food plant-based diets have better body mass index profiles than the people who are incrementally eating more animal-based foods. There’s good data from the Adventist studies as well as the EPIC, the European Prospective Investigation to Cancer in those populations. 

There’s good studies on that. Other studies as well, talking about people incrementally eat plant-based having a better BMI profile. I will also warn people that there are some people who are plant-based or vegan and they eat extremely low calorie diets. There’s dogma on the plant-based side, too. So some people say that, “Oh, you know, just eat plant-based,” and they want to be like fruitarian or eat just all vegetables and very little protein foods or grains or things like that, or be completely raw. I think those things maybe can be okay, but you have to be careful. You have to have one gram of protein per kilogram of body weight per day, like somewhere around there, that’s an adequate amount of calories, and people who are very underweight, there is a study that came out showing that they had, women who were very underweight, had increased rates of fractures in the plant-based group. 

And it’s probably just because they were so skinny. There were so many more skinny women in that group, and they had more fractures. So, especially for the plant-based women out there, don’t become too underweight. Make sure you’re consuming the right amount of calories and protein, and keep your body mass index, you know, sort of, maybe at around, above 20, you know, because below that you start seeing dramatic increases in fracture rates. So even on the plant-based side, there’s things to learn.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Sounds good. What do you think is the unanswered questions that remain? What would you like to say? I know you kind of mentioned a little bit about what the research could still be done. What do you think is needed really to get the message out and people can understand the science behind plant based diets.

Tushar Mehta, M.D.

Honestly, I think that the biggest challenge is misinformation. You know, people coming and talking about these paleo, keto, and quoting some study or something like that, or usually not quoting any study whatsoever, actually. If you look at a lot of these people who are promoting these things, and they give a talk, and there’s no articles referenced, right? I think that’s not the way to go. Or, you know, you can find some little study that will tell you that, I mean, you can eat, like your cell phone and it’ll be better for you. I don’t know. You know, there’s always some little study, rinky-dink study, on everything. What we need to do is we need to look at the existing body of literature carefully and not any one particular study alone, and amalgamate and combined our understanding after looking at the body of literature. 

And you’ll find that there is very, very good evidence that’s already out there. I don’t believe that there’s a missing link or anything like that, or so many missing studies. I think that we need to consistently do these studies to strengthen our understanding, further our understanding, improve the quality of studies. I’d like to see more studies. And this is being done, looking at diet quality, not just looking at if you’re plant-based or not plant-based, but looking at plant-based diet quality, right? So we’re looking at people who have high quality, low fat, whole food plant plant-based diets, adequately proportioned like that, and looking at those long-term outcomes. 

I think that’s the future of where this body of knowledge needs to go. And I believe we’ll see even stronger results when we do that. Because right now, in a lot of these plant-based groups, you’re seeing a combination of people who have bad plant-based diets and good plant-based diets, right? Although there have been now some studies, you’ll see them in the references I sent you, that do look at plant based, they look at healthy plant-based index. So they’re trying to assess diet quality. And I think these are initial attempts that can still be done better. So I think that’s where the body of literature needs to go, as well as doing more research on things like, let’s say, erectile dysfunction, let’s see more, you know, there’s a lot of… There’s mounting evidence regarding dementia. 

I’d like to see even more studies done in that category and other things. So I think that there’s still a lot of good research that’s ongoing and that’s being done. And it’s pretty exciting, because the nice thing is there’s consistency showing the benefits in terms of long-term benefits, okay? Beware of looking at rinky-dink little studies that come up with some little paleo thing or this or that, or any other thing, or even any little plant-based study that has claims that are out of proportion, even just plant based, it could be a garbage study. So, you know, we don’t want to pay attention to those, too. We want to whittle those out. Be aware of biomarker studies. We don’t want to just look at biomarkers. We want to look at clinical outcomes. I think that’s very important. Something may increase your homocysteine or your TMAO level or whatever it is. 

You know, we care about heart attacks. We care about dementia. We care about whether you die or not. Those are the things that are more important than biomarkers, except for the very traditional biomarkers that we use in medicine. Like, you know, glucose HbA1c, your cholesterol levels, blood pressure. I mean, those are the biomarkers that I think we have enough evidence that they’re important in and of themselves, right? So those are the things. And I also tell people when I give a talk, and I hope I remember to tell them every time, is don’t just listen to me. I’m giving this talk, right? I could be biased. I could be anything. 

I’m gonna provide you with a reference list. Go through my reference list and verify if the studies that I’m telling you about are consistent with what I’m saying. I think that’s very important, too. Don’t just listen to people, right? Go yourself. And what I try to do with my website plant-based data is try to make the data more accessible to people. So if you wanted to look up information on cardiovascular disease, and you go on Google and you look up cardiovascular disease, plant-based diet, you’ll find some information, but it’s gonna take you a very, very long time to come up with all the studies that are important, and then look at them and see if there’s this consistent signal between how the studies are done and the results that they’re getting, right? On our website, we sort of amalgamate them for you. Now you can take a look at them for yourself easier. So that’s a plug for our website that it’s a tool for people to use.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Yes, plantbaseddiet.com? Or what-

Tushar Mehta, M.D.

No, plantbaseddata.org.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Oh, sorry, plantbaseddata.org, okay, perfect.

Tushar Mehta, M.D.

Yes. Yes.

Sanjeev Goel, MD, FCFP (PC), CAFCI

And how would a person understand the quality of their own, let’s say diet, ’cause I think that’s the message I’m kind of getting from what you’re talking about today is that, if there is a difference between different types of diets, but quality of the diet is really important, you know? ‘Cause one could be having ice cream and be on a plant-based diet, so, I mean…

Tushar Mehta, M.D.

Right, right. Yes. Yeah. So, I mean, that’s important too. I mean, the principles of just general eating healthy for a regular person are, think of this. So whole foods or minimally processed foods, right? So ice cream, containing sugar, sugar is a highly processed food. We don’t want to eat those refined carbohydrates, the sugar and the fat that’s in there, right? Fat is a highly processed food, right? You’re extracting the fat, one thing, and leaving all the rest of the food behind, okay? So we wanna eat more whole foods, wanna eat beans and legumes and you know, vegetables and fruits and whole grains. 

Buy whole grain bread or whole grain flour to make your roti or that kind of stuff, so whole, and minimally processed. So a little bit of processing, you know, if you take a grain and you grind it, it becomes a flour. Okay. So that’s fine. That’s one level of processing. That’s probably okay. Now, if you start extracting all the different components of it and leaving behind just more of the starchy component and the gluten, and you get white flour, that’s a highly processed food. So if you make bread from just whole grain flour, that’s a minimally processed food. You just ground the flour, you’re making bread out of it. 

If you make tofu, you’ve used most of the soybean. If you eat edamame, that’s a whole food, right? That’s the whole soybean, and tofu and soy milk are kind of minimally processed foods. They’re still okay, as long as you’re not adding a lot of sugar to your, you know, don’t have the chocolate milk, soy milk, right? Don’t go there. Right? So eat whole foods, eat low fat. A little bit of fat is okay. Most of us are gonna eat a little bit of fat. It may be involved in the recipe, but just make sure it’s not too much, okay? And go for the healthy fats, healthier fats, like canola oil, soybean oil, olive oil is great. Flax seed oil is good. 

Avoid things like palm oil and coconut oil, which are high in saturated fats, also heavier environmental impact. Okay? So minimize the oil, but eat some of those healthier ones. If somebody has heart disease, pre-existing heart disease that they really want to have secondary prevention, they want to prevent that second heart attack, in these Dean Ornish and Caldwell Esselstyn studies show that you can go to almost zero fat. And I don’t like the word reversing heart disease. I like to use the word secondary prevention, which is the more medical terminology which I think is what actually happened, right? It prevented subsequent cardiovascular events and revascularization surgery. 

So you can do that. So whole food, low-fat, plant-based, and eat the variety, eat the rainbow, eat all the broad, different colors and variety of plant-based food. There’s so many different fruits, so many different vegetables, so many different legumes that are out there, lentils and beans. There’s international dishes, whether they’re from, you know, beans dishes that native people made right here in Ontario or something that people did in Asia or China or South America. There’s lots of different things out there. So eat that rainbow, eat that variety, but get enough of the different categories. Remember, you want to get enough protein. You should be getting roughly one gram per kilogram of ideal body weight per day. 

Make sure you’re getting enough of that protein. Make sure you’re eating adequate calories, meaning not too much and not too little, and that you’re having the variety of all the different food groups that I mentioned, right? Including nuts and seeds. That’s another great one, food groups you also include. And I think that’s the general thing, and then there’s lots of resources online that can help you. I think you had asked me about resources. There’s something called the Plantrician Project. You can look them up, Plantrician Project. 

You can look up PCRM, which is Physician’s Committee for Responsible Medicine. There’s a couple of great books that I recommend. There’s one called “Becoming Vegan.” And there’s another one called “Vegan For Life.” Now, even if you’re not becoming vegan and you just want to eat more plant-based, these are still great books, because they will guide you to shift in that direction, even if you’re not doing it 100%. So those are some good resources that are out there.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Perfect, no, that’s so helpful for our viewers. So I really thank you for your time today, Tushar.

Tushar Mehta, M.D.

Thank you, thank you. I’m also gonna plug my own lecture If you go to Plant Based Data, I have a lecture on plant-based diet in health. Check that out. I think it’s one lecture, kind of like 40, 45 minutes, where I cover all of this stuff in pretty good detail including things like taking your B12, stuff like that.

Sanjeev Goel, MD, FCFP (PC), CAFCI

I’m sorry, say that plug in one more time, where is exactly the lecture?

Tushar Mehta, M.D.

Okay, so you go to my website, plantbaseddata.org, look at the health section, and there’s a video by me there. Please also take a look at the environment section. And there’s also a pandemic section, because as people sort of vaguely know, this pandemic that we’re currently suffering from is a direct result of animal agriculture, and I have a podcast there also about the problem with animal agriculture and how that’s becoming a generator for viruses which put us at risk for future pandemics. There’s a big cost to current and future pandemics that come from animal agriculture. This is another big reason why plant-based diet is important.

Sanjeev Goel, MD, FCFP (PC), CAFCI

Yeah. No, thank you. I think Bill Gates just came out and said we should be reducing meat consumption to address climate change. And we didn’t get a chance to talk about all that, but that’s for a different podcast.

Tushar Mehta, M.D.

Different podcast. Beyond climate change, there’s many, many other benefits of plant-based diets with regard to the environment. But we would love to talk about that if you ever have me back on the show.

Sanjeev Goel, MD, FCFP (PC), CAFCI

All right, okay. Have a great day. Thanks so much.

Tushar Mehta, M.D.

Thank you, Sanjeev. Okay. Take care to everybody that’s out there.